Radio tuning device



Aug. 4, 1936. J. H. CLARK ET AL RADIO TUNING DEVICE Filed Sept. 18, 1955 5 Sheets-Sheet l 1936- J. H. CLARK ET AL RADIO TUNING DEVICE Filed Sept. 18, 1955 3 Sheets-Sheet 2 Au 4, 1936. J. H. CLARK ET AL 2,049,894

RADIO TUNING DEVICE Filed Sept. 18, 1955 5 Sheets-Sheet 3 3 m9 4.? -10 26 62 18 a7 a; 4 24 2 6] 63 50 62 9 167 44' V 17 (/6686 H Clark Ali/427g? A. L agairom Patented Aug. 4-, 1936 UNE'EED STATES FATENT OFFICE RADIO TUNING DEVICE Application September 18, 1935, Serial No. 41,041

15 Claims.

This invention relates to a radio tuning device and is more particularly concerned with means whereby the tuning or station selection may be more readily and easily accomplished, and by means of which an extremely fine degree of tuning is possible.

Heretofore, there have been two outstanding arrangements for obtaining a relatively fine degree of tuning. One of these arangements re- 10 sided in the use of the so-called Vernier style dial,

and the other in the utilization of a band spreader. The first system embodied a single variable tuning condenser which was actuated through a rotatably mounted dial having a manually actu- 15 atable knob directly movable with the dial for making rough adjustments of the condenser" For finer adjustments, an auxiliary knob 'was provided, this knob being in frictional engagement with the periphery of the dial, and of small 20 diameter compared to the diameter of the dial.

With this arrangement, the turning of the auxiliary knob would result in relatively small movement of the dial and consequently the tuning condenser. This arrangement was unsatisfactory 25 mainly due to the difiiculty in reading the graduations on the dial. It was extremely difiicult to secure different dial readings for stations which were very close together.

In the other arrangement, namely, the type em- 30 ploying a so-called band spreader, it has been the usual practice to provide a dial plate with two semi-circular scales thereon and to utilize two indicating hands which are respectively associated with the aforementioned scales. These 35 hands are rotatable about the same axis by means of a single knob and a clutching arrangement which enables this knob to be utilized in moving first one hand and its associated condenser for rough adjustment, and thereafter a second condenser, and the other hand for the finer adjustment. This arrangement, besides being inconvenient is relatively expensive due to the fact that two condensers are necessary.

To overcome the disadvantages of the arrangements heretofore used, this invention proposes to provide a single tuning means, such as a condenser, a single knob for varying the condenser setting, and a pair of concentrically disposed scales on a single dial plate, which are 513 traversed by simultaneously movable indicating hands, these hands being interconnected with the operating knob and relative to each other, so that the hands are simultaneously moved at different rates of speed. With this arrangement, 55 the more slowly moving hand would be utilized for making the rough tuning adjustment of the tuning condenser, whereas the hand which is rotated at the greater speed would be used for the finer adjustment of the condenser. This arrangement is advantageous in that a single op- 5 erating knob is used and in that this knob may be mounted remotely from the indicating dial, thereby in no way tending to obstruct the view of the dial during the tuning operation. Moreover, a single variable condenser is used, and it 10 is not necessary to use more than one condenser, as in the band spreader arrangement.

Moreover, in other of the prior art tuning device arrangements, various combinations of gears have been utilized for the purpose of microtuning. In the main, these arrangements have been unsatisfactory due to the back lash or lost motion in the gears. While such arrangements were all right in principle, they were unsatisfactory from a commercial viewpoint as the back lash could, it was thought only be eliminated by providing extremely accurately cut gears having teeth which could be closely meshed. Of course, to furnish such gears was so costly that these arrangements were rendered uncompetitive.

It is therefore an object of the present invention to utilize standard gears in such a manner that back lash and lost motion are practically eliminated, with the result that the herein described tuning device is relatively inexpensive and therefore very competitive.

Other objects and features of this invention will more fully appear from the following detailed description taken in connection with the accom panying drawings which illustrate several embodiments thereof, and in which:

Figure 1 is a view in elevation showing a fragmentary portion of a radio panel having a tuning device embodying the features of the present invention mounted thereon;

Figure 2 is a similar view with the radio panel and indicating mechanism removed to show the connections between the manually operable knob and the tuning means;

Figure 3 is a plan view showing the operative 5 instrumentalities of the present invention as utilized in connection with a tuning condenser;

Figure 4 is a sectional View, taken substantially on line IVIV of Figure 5, to show the detailed arrangement of gears as utilized in one form of the invention;

Figure 5 is an enlarged fragmentary sectional view, taken substantially online V-V of Figure 7 2, to show additional details of this form of the invention; v

Figure 6 is a view similar to Figure 4, showing a modified form of the invention;

Figure 7 is a view similar to Figure 5, in connection with the modified form of the invention;

Figures 8 and 9 are detailed views of the gears utilized in the modified form of the invention;

Figure 10 is an enlarged fragmentary longitudinal sectional view of still another modification of the herein described invention;

Figures 11 and 12 are enlarged fragmentary transverse sectional views of the same, illustrating the operation of the stop means, taken substantially on line XI-X[ of Figure 10; and

Figure 13 is an enlarged fragmentary view showing means for eliminating back lash between meshed gears of the present invention.

As shown on the drawings:

In Figure 1 of the drawings, we have chosen to show a radio panel I!) which may constitute. a part of any modern radio set, which includes a tuning knob I l' of the usual construction; which is accessible from the forward side of thepanel. The'tuning dial of the set is generally indicated at-IZand will subsequently be described in detail,

Extending rearwardly of the panel is the usual type of'multi-plate variable condenser which is generally indicated by the nu'meral'l3l' Thiscondenser includes cooperatively associated fixed plates (not shown) and movable plates I l disposed alternately between the fixed plates in a manner well known in the art. The movable plates, as is the usual custom, are mounted for concerted rotational movement with a rotatabls mounted shaft I5. This shaft is suitably supported at bearing po'ints throughout its length in the condenser framework, as shown at- H5 in Figure 5.

At the outermost extremity of the shaft 5, at the forward end of the condenser, there is rotatably mounted a sleeve [1 having at its innermost end a pulley [8' which is rotatable with the sleeve. In this case, the pulley is of'cupshape with'its' peripheral wall formed to definea circumferentially extending groove 19 which is adapted toreceive a belt '20, as shown in Figures 2 and 3, this belt' being trained over .a driving pulley'2l' on a rotatably mounted shaft 22. This shaft supports, at its outer endon the forward side of the panel l0, the manually operable knob H.

The sleeve IT with the pulley I8 is retained against axial movement of thesh'aft [5 in a direction towards the condenser by means of a hub member 23 which is-fixedly'secured relative to the'sh'aft" l5 and-is disposed on the shaft with its inner end abutting a frame member 24 'of the condenser framework and its outer end engaged by the inner end of' the sleeve H. The outermost end of this hub extends through' a U-shaped bracket 25 in which it is rotatable, the legs of this bracket being secured respectively-to the frame member 24 of the condenser. I

The' bracket" 25'rigidly supports a gear 26 against movement with thehub 23, the hub 'in this case extending through the gear 26. A gear 21 is carried at the outer extremity of this end ofthe hub and is fixedly secured thereto for rotation with the hub. The teeth of the gears 26 and 21 are engaged by'the teeth of a common gear 28 whichis rotatably mounted on an axle pin 29,

this pin being radially spaced from the center of rotation of the-pulley l8. It will therefore be observed that as the pulley isTotated, the axle pin 29 together with the gear 28 will be revolved as a unit about the center of rotation of the pulley, and at the same time the gear 28 will be rotated on its axis due to its meshing with the fixed or stationary gear 26.

The gear 28 also serves as an idler to interconnect the gears 26 and 21, and it will be apparent that if the gears 26 and 2'! are provided with a different number of teeth-for example, if the gear 25 is provided with fifteen teeth and the gear 21 with sixteen teeth, then with fifteen teeth on the gear 28, one revolution of the'pulley will cause the gear 21 to advance one tooth. This movement of the gears will therefore advance the shaft l5 a relatively small amount when the pulleyand consequently the sleeve I! are moved through a complete revolution.

It will be evident that by cutting one less tooth on one of the gears 26 and 21, there will be a tendency for slight backlash or play, when actuated through the common gear 28, as the cut of the teeth on the gears 26 and 21 will necessarily be'slightly different. This is taken care of by providing a coil spring which extends around the hub 23 and has one end anchored therein and its other'end anchored in the bracket 25. This spring opposes rotation of the shaft 15 in one direction and causes the teeth of the gears 26, 21 and 28 to always be held tightly in engagement as the tuning condenser is operated.

The device is installed on a radio panel as l shown in Figure 1, with the outer end of the sleeve l1 and shaft [5 projecting outwardly of the forward face of the panel. The outer end of the shaft 15 is threaded to receive a screw 31 by means of which an indicating hand 32 is secured to the end of the shaft for rotation therewith. At the outer end of the sleeve IT, there is secured an indicating hand 33 which may be splined or otherwise attached to the sleeve.

Referring to Figure 1, it will be observed that associated withthe hands 32 and 33 is a dial plate 34 which is providedwith a pair of concentrically disposed tuning scales 35 and 36'. The scale 35 has spaced graduations bearing tuning indicia which may be representative of the wave lengths to which the set is tuned. Since the indicating hand 32moves relatively slow, the graduations on the scale 35 are indicative of relatively large variations in the position of the movable condenser plates. For example, these graduations may be numbered 500550, etc.

The scale 36 which is associated with the indicating hand 33' is extended preferably through 360 degrees and is provided with graduations bearing indicia, for example, 0-5--I0, etc. Since the hand 33 moves relatively faster than the hand 32, the fine tuning adjustments may be accomplished on the scale 36. Both indicating hands are moved in the same direction simultaneously and the setting for a given station would be indicated by a reading composed of the combined indicia of both scales 35 and 35. For example, a station might be logged at 950-10.

The modified form shown in Figures 6 to 9, inclusive, differs from the previouslydescribed form of the invention only in the manner of accomplishing the gear connections between the shaft 15 and sleeve H. In the modified form of the invention, like numerals have been used to indicate the corresponding parts of the structure. In this form of the invention, the single gear 28 is replaced by a pair of gears 3i and 38 which are secured together for unitary rotation on the axle pin 29. The gears 3'! and 38 are provided with a similar number of teeth, in this case fifteen teeth each. Since the gear 23 contains fifteen teeth and the gear 21 contains sixteen teeth, the teeth of the gears 31 and 38 may be cut so as to properly mesh without in any way interfering with the engagement of the teeth on the gears and 21, thereby substantially eliminating lost motion and permitting the elimination of the take-up spring of the previously described form of the invention.

In addition, it will be observed that the axle pin 29 instead of being secured directly in the pulley I8, is supported on a pivotally mounted arm 39 which is pivoted at one end as shown at 40 to the pulley E8. The free end of the arm 39 is connected to one end of a tension spring 4|, the other end of this spring being anchored as at 42 to the pulley. This spring acts to rotate the arm 39 in a counter-clockwise direction and cause the gears 3'! and 38 to be held in resilient engagement with the gears 26 and 21.

The arrangement shown in Figure 10 is in the form of an attachment which may be readily applied to any tuning device such as a condenser and operates on the same general principles as the arrangement previously described. The main difierences between the arrangement shown in Figure 10 and the other arrangement resides in the utilization of stop means and improved means for taking up back lash or lost motion in the gearing.

It will be noted that instead of securing the indicator hands 32 directly to shaft I5, the shaft I5 in this arrangement is terminated near the frame member 24 and a short shaft extension 43, which in this case has the indicator hand 32 secured thereto, is secured to the shaft I5 by means of a coupling 44. This coupling is cylindrical in form and has one end bored to receive anend of the shaft 43 and its other end bored to fit over the end of the shaft [5, this latter end being secured to the shaft l5 as by a set-screw 45.

The bracket 25 in this case forms a bearing support for the coupling 44. A gear 46 having 37 teeth in this case surrounds a contracted portion of the coupling 44 and is fixedly secured to the bracket 25 so that the coupling is free to move relative to this gear.

Spaced from the gear 46 is a double gear composed of a fixed part 4'! which is secured to the coupling 44 for movement therewith, and a movable part 48 which is free to rotate relative to the coupling 44. The two parts 41 and 48 are each provided with the same number of teeth, in this case 37 teeth each. The purpose of the double gear will subsequently be explained in more detail.

This double gear has the teeth of both parts meshing with the teeth of a gear 49 which is fixedly secured on a hub 50 for rotation therewith. The gear 49 is provided with 31 teeth in this case.

Also mounted on this hub is another double gear composed of a fixed part 5| which is rigidly secured to the hub 50 for rotating therewith, and a movably mounted part 52 which is supported for movement relative to the hub and part 5|. Both parts 5! and 52 have a corresponding number of teeth, in this instance 38 teeth.

The hub 55, it will be observed is mounted on a stud 53 which is tapered from its outermost extremity toward its point of support on the pulley l8. The hub 58 is urged outwardly on this tapered stud by means of a leaf spring 54 so that if there is any wear between the hub and stud, this wear will bev taken up by the spring, whereby lost motion is eliminated.

The double gear composed of parts 5| and 52 has its teeth meshing with the teeth on gear 46. By reference to Figure 13, the double gear arrangement will be explained in detail. Taking for example, the double gear having parts 5| and 52, each of these parts is provided with arcuate slots 55 and 56 respectively, these slots being in circumferential alignment and angularly offset. An open ended ring shaped spring 5? surrounds the hub 55 and is disposed with its deflected ends 58 and 59 in the arcuate slots of the gear parts 5: and 52.

The ring shaped spring 51 is so constructed that the ends 55 and 59 must be brought together slightly in order to insert the ends in the slots, whereby the tendency of these ends to move apart will cause the ends to abut the opposed ends of the respective slots 55 and 56, thereby tending to shift the teeth of the movable part 52 relative to the fixed part 5! of the double gear. This action is clearly shown in Figure 13. It will therefore be evident that this action will at all times cause the teeth of the double gear to tightly mesh with the mating gear and that there will be no back lash or lost motion as the teeth of the gears become worn. The action which has just been described in connection with the double gear having parts 5! and 52, also takes place in connection with the other double gear havin parts 4'! and 48.

Removal of the sleeve i'l, pulley l8 and the gears supported thereby, from the shaft 43 is prevented by means of a washer 50 which surrounds the coupling 44 and is disposed between the gear 46 and the double gear having parts 47 and 43. This washer extends out sufiiciently to project beyond the teeth of the gear 46 and acts as a barrier against movement of the pulley assembly in an axial direction.

Novel stop means are provided to enable the pulley Hi to be normally rotated through a predetermined number of revolutions in either a forward or reverse direction, after which the stop means comes into play to stop further movement in the direction in which the pulley is being moved.

For this purpose, the stud 53 at its outer end is contracted to form a projecting portion 6! which moves in a circular path as the pulley is rotated.

Pivotally mounted on a pivot pin 62, as shown in Figures 11 and 12 is a rocker arm 63 having a pivotal bearing at its center on the pivot pin 62. The opposed ends of this rocker arm are deflected to respectively form right angularly disposed abutment projections 64 and 65 which are in the plane of rotation of the projection 6| of the stud 53.

The rocker arm on the side toward the coupling 44 is provided with a pair of spaced teeth 56 and 61 which are arranged to cooperate with a cam surface 58 formed on the coupling 44. At its respective ends, the cam surface 58 is terminated in a recess 69 and recess 70. Moreover, it will be observed that the cam surface 68 is depressed relative to the normal surface of the coupling 44, whereby substantially radially extending abutment surfaces H and i2 are formed.

Referring to Figure 11, it will be observed that the abutment projection 64 is in such position as to intercept the projection 5i and prevent further movement of the pulley I 8 in a counterclockwise direction. Also, the tooth 66 of the rocker arm is disposed in the recess 69 and the rocker arm has been rotated in a clockwise direction due to the abutment of surface H with the tooth 66.

From this position, the only movement which may follow of the pulley i8 is in a clockwise direction. Referring to Figure 12, it will be seen that as soon as the pulley starts to move, the coupling M also starts to move in a clockwise direction. This movement operates to move the cam so that the tooth 66 moves out of the recess 69 onto the cam surface 68. The rocker arm is therefore shifted a slight amount in a counterclockwise direction, this shifting being suilicient to move the abutment projection 65 out of the line of travel of the projection M. The pulley may therefore be moved a predetermined num ber of revolutions in a clockwise direction, or until the tooth 6'! falls into recess iii and engages the abutment surface l2. This will cause the rocker arm to be further shifted in a counterclockwise direction until the abutment projection 65 is in such position as to intercept the pro- V jection 6i, whereupon further movement in a clockwise direction is prevented.

From the foregoing description, it will be apparent that the present invention provides an improved radio tuning device which permits the tuning of a station to be readily and easily accomplished; which utilizes a single operating knob and single condenser; which enables the operator of a radio to secure an extremely fine degree of tuning, and which includes a gear train that is practically free of back lash or lost motion.

Now, it is of course to be understood that although we have described in detail several embodiments of our invention, the invention is not to be thus limited but only insofar as defined by the scope and spirit of the appended claims.

We claim as our invention:

1. The combination comprising means including a rotatable shaft for varying the electrical charact ristics of a circuit, a gear fixedly mounted on said shaft, a second gear surrounding said shaft and held against movement with the shaft, said gears having a different number of teeth thereon, a driven pulley on said shaft, an idler gear rotatably mounted on said pulley with its teeth commonly engaging the teeth of said other gears, the axis of rotation of the idler gear being revolved about said shaft by the rotation of said pulley, means manually operable to rotate said pulley, indicating members respectively movable with said shaft and said pulley, and dials respectively associated with said members, said dials bearing tuning indicia.

2. The combination comprising means including a rotatable shaft for varying the electrical characteristics of a circuit, spring means opposing the rotation of said shaft in one direction, a gear fixedly mounted on said shaft, a second gear surrounding said shaft and held against movement with the shaft, said gears having a different number of teeth thereon, a driven pulley rotatably mounted on said shaft, an idler gear rotatably mounted on said pulley with its teeth commonly engaging the teeth of said other gears, the axis of rotation of the idler gear being revolved about said shaft by the rotation of said pulley, whereby said pulley and shaft are rotated at diiferent speeds, means manually operable to rotate said pulley, indicating members respectively movable with said shaft and said pulley, and dials respectively associated with said members, said dials bearing tuning indicia.

3. The combination comprising means including a rotatable shaft. for varying the electrical characteristics of a circuit, means resiliently opposing .the rotation of the shaft in one direction, a pair of dissimilar gears surrounding the shaft, one of said gears being rotatable with the shaft and the other non-rotatable therewith, a gear common to said pair of gears having its axis of rotation mounted for revolution around said shaft, manually operable means for revolving said axis, and dial means to indicate the positions of said shaft and axis, said dial means having tuning indicia thereon.

i. The combination comprising means including a rotatable shaft for varying the electrical characteristics of a circuit, means resiliently opposing movement of the shaft in one direction, a rotatable member arranged for manual operation, connections between said member and shaft including gears interconnected in such a manner as to cause the member and shaft to rotate at different speeds, and means for individually indicating the respective movements of the shaft and member, said latter means having tuning indicia associated therewith.

5. The combination comprising means including a rotatable shaft for varying the electrical characteristics of acircuit, a rotatable member arranged for manual operation, connections be tween said member and shaft including gears interconnected in such a manner as to cause the member and shaft to rotate at difierent speeds, and means for individually indicating the respective movements of the shaft and member, said latter means having tuning indicia associated therewith.

6. Thecombination comprising variable tuning means having a rotatable shaft, a rotatable member .arranged for manual actuation, a pair of gears surrounding said shaft, one of said gears being rotatable with the shaft and the other being non-rotatable with the shaft, a pair of rigidly connected idler gears having a common axis mounting on said member and respectively meshing with said first pair of gears, said gears being of, such relative ratios as to cause said shaft to rotate at a slower speed than said member, and indicators respectively movable with the shaft and member and individually cooperating with dials having tuning indicia thereon.

7. The combination comprising variable tuning means having a rotatable shaft, a rotatable member arranged for manual actuation, a pair of gears surrounding said shaft, one of said gears being rotatable with the shaft and the other be ing non-rotatable with the shaft, a pair of rigidly connected idler gears having a common axis resiliently mounted on said member and respectively meshing with said first pair of gears, said gears being of such ratios as to cause said shaft to rotate at a slower speed than said member, and indicators respectively movable with the shaft and'member and individually cooperating with dials having tuning indicia thereon.

8. In combination with means for Varying the electrical characteristics of a tuning circuit, said 9. A radio tuning attachment adapted for connection to the rotatable shaft of a tuning condenser and comprising, a supporting bracket, an indicator including a member rotatably mounted in said bracket, means for removably connecting said member and shaft for unitary movement, a pulley rotatable on said member, a second indicator, means connecting said pulley and second indicator, a gear train interconnecting said pulley and member, whereby, when the pulley is rotated, the member will be rotated at a slower speed, a stud carried by said pulley, cam means carried by said member, and stop means on said bracket actuated by said cam into the path of movement of said stud in response to a predetermined number of revolutions of said pulley.

10. In a radio tuning device, a bracket, an indicator including a shaft rotatably mounted in said bracket, a second indicator including a rotatable member adapted to bedriven from a remote point, speed reducing means interconnecting said member and shaft, whereby the shaft is rotated at a slower speed than said member, and stop means responsive to the movement of said shaft for intercepting the movement of said member in either a forward or reverse direction after a predetermined number of revolutions of said member in that direction.

11. A radio tuning device for varying the electrical characteristics of a circuit, comprising a rotatable indicator, a second rotatable indicator, means for simultaneously driving said indicators at different speeds, and means operative in response to the movement of one of said indicators to intercept and limit the movement of the othe of said indicators.

12. A radio tuning device for varying the electrical characteristics of a circuit comprising a rotatable indicator, a second rotatable indicator, one of said indicators being arranged to make a plurality of revolutions during a partial revolution of the other indicator, means for simultaneously driving said indicators, and stop means normally permitting said one of the indicators to revolve and operative in response to a predetermined movement of said other indicator, to intercept further movement of said one of said indicators.

13. A radio tuning device for varying the electrical characteristics of a circuit comprising a rotatable indicator including an abutment member, a second rotatable indicator, said first indicator being arranged to make a plurality of revolutions during a partial revolution of said second indicator, means for simultaneously driving said indicators, movable stop means normally enabling rotation of said first indicator, and means responsive to a predetermined movement of said second indicator for moving said stop means into the path of travel of said abutment member, whereby the rotation of said first indicator is intercepted.

14. A radio tuning device for varying the electrical characteristics of a circuit comprising a rotatable indicator, an abutment member rotatable with said indicator, a second rotatable indicator, said first indicator being arranged to make a plurality of revolutions during a partial revolution of the second indicator, unitary drive means for said indicators, an elongated arm pivoted intermediate its ends for rocking movement and having right angularly disposed abutment surfaces at its ends normally positioned out of the path of travel of said abutment member, and cam means responsive to a predetermined movement of second indicator in one direction for rotating said arm in a direction to move one of its abutment surfaces to effective position, and a predetermined reverse movement to move the other abutment surface to effective position.

15. The combination comprising means including a rotatable shaft for varying the electrical characteristics of a circuit, a pair of dissimilar gears surrounding the shaft, one of said gears being rotatable with the shaft and the other nonrotatable therewith, a gear having a double set of teeth respectively meshing with said pair of gears, a tapered stud forming an axis for said gear, said stud being supported for revolution about said shaft, spring means urging said gear towards the larger end of said stud, means manually operable to revolve said stud, and dial means respectively indicating the angular movements of said stud and shaft.

JESSE H. CLARK. HILDING A. LAYSTROM. 

